@dougwrites, No. This essentially just adds hookable handling while effectively emulating the exact same behavior as before. In other words: it makes it possible for the site manager to control what is a "large network" for the purposes of their own system, without relying solely on the "magic numbers" that are in place in the 3.0 to 3.2.1 releases. While an alternative is to use a conditional define for the limit, the method used here allows for a dynamic implementation. For example, say you only want to allow user 1 to have full scope (treat it as full access), while limiting others. This would do that pretty easily.

In class-wp-ms-users-list-table.php, why add trailing and leading '*' to the search term for small networks? This should be left for the user to do so that they can choose to get an exact match, or not. Searching for 'matt' and getting hundreds/thousands of '*matt*' matches is annoying.